It has been proposed heretofore to provide a steering axle assembly for an industrial-type vehicle, especially a floor vehicle such as a fork-lift truck, with an elongated axle body which is secured to the vehicle frame or chassis with at least limited pivotal mobility about an axis lying in the vertical longitudinal median plane of the vehicle and transverse to the axle body.
In general, a pair of wheel axles are pivotally mounted at the opposite ends of this body and are connected to a steering linkage which swings these wheels. This steering linkage can include a pivot for a knuckle which can be connected by respective tie bars to axle carriers each of which has a respective wheel-carrying axle fixed thereto.
A hydraulic-cylinder arrangement may be provided to displace this linkage.
Such systems have been found to be effective in providing a relatively small turning radius as is necessary for the high maneuverability required for floor vehicles such as fork-lift trucks.
The limited swingability of the axle body is important to permit the axle assembly to adjust to irregularities in the floor or ground surface over which the vehicle travels even where the wheels of the vehicle carry elastic, i.e. pneumatic tires.
Conventional axle assemblies for the steerable wheel of a vehicle generally comprise a pair of journal blocks which mount the axle assembly upon the vehicle frame or chassis, these journal blocks having aligned bores parallel to the longitudinal axis of the vehicle and hence perpendicular to the longitudinal dimension of the axle body.
A pivot bolt or pin traverses these bores and permits the axle body to swing about the axis of the pin or bolt and hence with limited mobility about an axis parallel to the longitudinal axis of the vehicle.
This mounting assembly applies the vertical loading forces of the vehicle to the axle assembly.
Since the axle assembly must also be subjected to the braking forces and forces resulting from the rolling resistance, it is subjected to shocks of various type during normal operations and when the vehicle wheels are partly or wholly blocked or encounter irregularities.
The journal blocks must thus be provided with sliding surfaces capable of absorbing forces parallel to the axis of the pivot pin or bolt in both directions. These forces produce moments which are, in turn, transferred to the bolt or pivot pin.
Conventional assemblies of this type have not been found to be fully successful in absorbing all of these various forces and shocks in a reliable manner.
In addition, the linkage between the axle body and the vehicle body or chassis is relatively expensive, requires considerable labor in mounting and repair, and also involves considerable work in adjusting the mounting arrangement to exclude undesired play.